Magnesium alloy, which is lightweight and high in specific strength, has been used for the housing case of mobile devices, such as a cellular phone and a notebook personal computer, and a structural material for an automobile's parts and the like. In particular, in recent years, the market has been requiring a magnesium alloy joined part to be thin to further reduce its weight. The thinning of a magnesium alloy joined part, however, results in a decrease in its rigidity. To prevent this decrease, it becomes necessary to provide a reinforcing material.
To provide a magnesium alloy base material with a reinforcing material, it is conceivable to form, by machining, the reinforcing material as a body unified with the base material (Patent Literature 1). It is also conceivable to join the reinforcing material to the base material. The concrete means of the joining include a means of bonding a reinforcing material to the base material with an organic adhesive sheet.